[NGO Admin; Specialist/ Cazuri/ Plan de interventie] Lack of Guidance on Service Configuration in 'Plan de Interventie' Module

#### Description
In the "Plan de interventie" module, the user can open the "Adauga Serviciu" modal even when no services are configured.

#### Steps to Reproduce
1. Log in as Admin/Staff
2. Access a center without any services configured in the "Nomenclator servicii" page
3. Go to the "Cazuri" page and select a case without a "Plan de interventie" configured
4. Click on the "Creeaza plan" button
5. Click on the "Adauga Serviciu" button

#### Expected Result
5. The "Adauga Serviciu" button is unclickable (disabled)

#### Actual Result
5. The "Adauga Serviciu" modal opens even though no services are configured

#### Observation
The flow is confusing because the user cannot submit the form due to the mandatory "Tipul serviciului" field, which is empty.
Additionally, the user is not informed about the required action to configure services before adding one.